Smith, Clinton J.Shankar, RajiLaderer, MatthewFrish, Michael B.Loncar, MarkoAllen, Mark G.2019-10-032015Smith, Clinton J., Raji Shankar, Matthew Laderer, Michael B. Frish, Marko Loncar, and Mark G. Allen. 2015. “Sensing Nitrous Oxide with QCL-Coupled Silicon-on-Sapphire Ring Resonators.” Optics Express 23 (5): 5491. https://doi.org/10.1364/oe.23.005491.1094-4087http://nrs.harvard.edu/urn-3:HUL.InstRepos:41461265We report the initial evaluation of a mid-infrared QCL-coupled silicon-on-sapphire ring resonator gas sensor. The device probes the N2O 2241.79 cm(-1) optical transition (R23 line) in the nu(3) vibrational band. N2O concentration is deduced using a non-linear least squares fit, based on coupled-mode theory, of the change in ring resonator Q due to gas absorption losses in the evanescent portion of the waveguide optical mode. These early experiments demonstrated response to 5000 ppmv N2O.en-USJournal Article2019-10-0310.1364/OE.23.005491